Estrus synchronization of Brahman cows with prostaglandin F29 analogue and progesterone-estrogen combination.

To study the effect of prostaglandin F29 analogue and progesterone-estrogen combination as estrus synchronizing agents, twenty-five non-lactating and normally cycling Brahman cows were used. Cows exhibited estrus at mean intervals of 81.0 +- 11.65, 82.2 +- 14.70, and 72.8 +- 1.34 hr after single injection of a prostaglandin F29 analogue through intraovarian, intrauterine, and intramuscular routes at the dose regimen of 0.1, 0.5, and 2.0 ml, respectively. Animals administered with Syncro-Mate B (SMB), a norgestomet-estradiol combination, manifested estrus at an average interval of 47.6 +- 2.32 hr. Time interval to estrus occurrence were similar among the three prostaglandin treated groups. However, the SMB treated cows exhibited heat signs significantly (P<.05) earlier than the first two groups synchronized with prostaglandin analogue. The number of animals exhibiting estrus after each treatment were the same. Estrus was not observed in any untreated animals before day 19 of their estrous cycle. The regression of corpus luteum (CL) followed by follicular development was initiated within 24 hr in majority of the prostaglandin treated groups. Complete luteolysis and development of mature follicles were detected in 72 hr except in one ovarian injected and another uterine treated cows. There were no significant differences in terms of time interval of these ovarian changes in prostaglandin treated groups. In the SMB treated animals, no palpable CL could be detected even at the time of inplant removal and mature follicles were palpated by 48 hr. Swelling and reddening of the vulva, copious vaginal mucous discharge, sniffing of the vulva, mounting activity and standing still while mounted by the herdmates were the commonly observed estrus signs and behaviors. Pregnancy diagnosis by rectal palpation at 2 to 3 months after AI [artificial insemination] confirmed 80, 60, and 60 percent conception rates in prostaglandin treated groups through intramuscular, intrauterine and intraovarian routes; 40 and 60 percent in SMB treated and untreated groups, respectively. However, the differences between treatment means were not statistically significant.